The present invention relates to an aerostatic bearing for an open-end spinning device with a spinning rotor.
An open-end spinning device of the type in which the spinning rotor is supported in bearing disks and where an axial force is exerted on the spinning rotor via the bearing disks, whereby the spinning rotor is supported axially by its shaft on an aerostatic axial bearing, is known from EP 0 435 016 A2. It is provided with a bearing plate which, together with the end of the rotor shaft, produces a low-friction pairing of materials. Here the air flows out into the bearing gap from the bearing plate, so that an air cushion forms between the rotor shaft and the bearing plate. In normal operation no contact takes place between the rotor shaft and the bearing plate, so that a practically wear-free axial bearing is provided. In the operation of open-end spinning rotors such rough operating conditions occur however at times, e.g. due to imbalance in the spinning rotor, that contact between the shaft end and the bearing plate does occur. In an open-end spinning rotor, such contact does not at all mean that the aerostatic bearing is damaged as a low-friction pairing of materials is used between rotor shaft and bearing plate. Furthermore, the bearing plate is designed so that it may become worn in case of overload of the axial bearing, so that the bearing is not destroyed rapidly. The wear of the bearing plate of the axial bearing is not much of a problem, but it is important that the spinning rotor, i.e. in particular its axial bearing surface, is not itself subjected to wear due to the wear of the axial bearing. This would practically mean that a new spinning rotor would have to be used, since the spinning rotor would then no longer have a suitable bearing surface and a repair of the bearing surface would be most impractical because of cost and technical reasons. Damage occurs in particular if the bearing plate of the axial bearing, which is made of a wear-resistant carbon material, becomes used up and the rotor shaft then comes into contact with other components of the axial bearing or possibly with a choke which is usually made of a metallic sintered material. Spinning operation is hardly possible any more with a heavily worn or damaged axial bearing because the fibers are no longer fed correctly into the spinning rotor. In spite of this, it occurs in practice that spinning rotors, together with an already heavily worn axial bearing, are continued in operation because the fact that the axial bearing is worn is not recognized.
EP 0 190 440 A2 also discloses an open-end spinning device of this type in which the spinning rotor bears axially upon an aerostatic axial bearing. Since this is a spinning rotor without shaft, it bears directly upon its axial bearing. The bearing plate in this case is ring-shaped, as a magnet is provided in the center so that an axially acting force is exerted upon the spinning rotor. Compressed air is conveyed via the bearing plate into the bearing gap between spinning rotor and bearing plate. A bearing plate which has been worn beyond an admissible value can here also lead to damage or destruction of the spinning rotor or even of its drive.